Cuts and Calibration

TOUCHSTONE carries the following Standard Calibrated Shapes in its current inventory (In addition to 39 fancy cuts:

	Round		Marqise
	Oval		Trillion (Trilliant)
	Square (Carre)		Baguette
	Octagon (Emerald)		Heart
	Pear		Princess Square

Calibrated size

Popular gemstones are sold in calibrated sizes. This means that gemstones are sold in sizes to fit most commercial jewelry, such as rings, earrings and bracelets. If you are working with a jeweler on a custom piece, you can purchase any size gemstone because the jeweler will size any piece to match your stone.

Round	Pear	Oval	Octagon & Emerald Cut	Trillion	Marquise	Square & Princess Cut	Heart
2 mm	5 x 3 mm	4 x 3mm	5 x 3 mm	4 x 4 mm	4 x 2 mm	4 x 4 mm	5 x 5 mm
2.5 mm	6 x 4 mm	5 x 3 mm	6 x 4 mm	5 x 5 mm	5 x 2.5 mm	5 x 5 mm	6 x 6 mm
3 mm	7 x 5 mm	6 x 4 mm	7 x 5 mm	6 x 6 mm	5 x 3 mm	6 x 6 mm	7 x 7 mm
3.5 mm	8 x 6 mm	7 x 5 mm	8 x 6 mm	7 x 7 mm	6 x 3 mm	7 x 7 mm	8 x 8 mm
4 mm	9 x 6 mm	8 x 6 mm	9 x 7 mm	8 x 8 mm	7 x 3.5 mm	8 x 8 mm	9 x 9 mm
5 mm	10 x 7 mm	9 x 7 mm	10 x 8 mm	9 x 9 mm	8 x 4 mm	9 x 9 mm	10 x 10 mm
6 mm	12 x 8 mm	10 x 8 mm	11 x 9 mm	10 x 10 mm	10 x 5 mm	10 x 10 mm	11 x 11 mm
6.5 mm	13 x 9 mm	11 x 9 mm	12 x 10 mm	11 x 11 mm	12 x 6 mm	11 x 11 mm	12 x 12 mm
7 mm	14 x 9 mm	12 x 10 mm	14 x 12 mm	12 x 12 mm	14 x 7 mm	12 x 12 mm
8 mm	15 x 10 mm	14 x 10 mm	16 x 12 mm	13 x 13 mm	16 x 8 mm	13 x 13 mm
9 mm	16 x 12 mm	14 x 12 mm	18 x 13 mm	14 x 14 mm	18 x 9 mm	14 x 14 mm
10 mm	18 x 13 mm	16 x 12 mm	20 x 15 mm	15 x 15 mm	20 x 10 mm
11 mm	20 x 15 mm	18 x 13 mm	25 x 18 mm	16 x 16 mm
12 mm
13 mm
14 mm

Purpose:

Most gem settings come in standard sizes. If a gemstone does not fit in a standard setting, the setting needs to be custom made which involves more labour and therefore more expense. If the value of a stone makes it worth cutting for maximum yield, then it makes sense to pay for a custom-made setting. Buyers take note; sometimes the cost of a custom setting isn't justified by the value of the gemstone.

Sizes:

If a gemstone is not the precise size for a setting, a skilled jeweler can alter a setting to accommodate the gemstone size.  All round gemstones can be put in a standard setting but other shapes require several factors to be considered.  If a gemstone is less than one carat it can be within .1 mm of the setting size. Gemstones over one carat can be accommodated if they have a .2mm variance and sometimes more.

Weights:

Weight charts are based on diamonds cut to exact proportions.  Coloured gemstones usually weigh more than their chart sizes as they are cut with greater volumes than diamonds.  The density of the gemstone will also affect its weight, so the point is to use the weight charts as a starting point for estimating gemstone weights.

For example:

• 6.5 mm round diamond = 1 carat
• 6.5mm round sapphire = 1.14 carats
• 6.5mm round opal = .61 carats